Fluid motor



C. B. LIVERS FLUID MOTOR Aug. 1, 1961 Filed July 15, 1959 INVENTOR. CHFPLOS 5. L./ VEES Wm VM imi ATTGRN EYS United States Patent U 2,994,306 FLUID MOTOR Carlos B. Livers, North Hollywood, 'Calif., assignor to Sprague Engineering Corporation, Gardena, Calif., a corporation of California Filed July 13, 1959, Ser. No. 826,541 9 Claims. (Cl. 121-114) This invention relates to fluid motors of the wobble plate type and more particularly to motors embodying pistons having the dual function of acting as means for transforming fluid pressure into mechanical motion and of acting as valves to control fluid flow to and from the cylinders in which the pistons work.

It is an object of the invention to provide an improved motor of the general type indicated characterized by more compact and eflicient elements and operation.

Another object is to provide a fluid motor of novel construction embodying a plurality of cylinders disposed about a central shaft, the cylinders being parallel to the shaft, and housing pistons engageable with a wobble plate on the shaft, wherein the pistons and cylinders are arranged in groups with the pistons in each group controlling the fluid passages to and from the cylinders of the particular group, each group of cylinders and pistons being in effect a motor in itself in conjunction with the shaft and Wobble plate. By way of example, in a motor having twelve cylinders there would be three sets or groups of four cylinders each, the cylinders of each group being spaced at 90 intervals circumferentially of the shaft and each piston controlling the fluid passages to a cylinder disposed 90 from it.

A further object is to provide a motor of the type indicated in which novel means is provided for establishing communication between the cylinders and the valving means. In this connection it is an object to provide a novel helically grooved sleeve which serves to provide fluid passages for flow of fluid to and from the cylinders and which also serves as a support for the shaft bearings.

Another object is to provide a motor in which the cylinders and fluid passages thereto are provided by a concentric pair of members, fitted one within the other, the outer one of which has the cylinders or piston chambers formed therein and the inner one of which is formed with a peripheral series of helical channels which serve as fluid passages to and from the cylinders.

These and other objects will be apparent from the drawing and the following description. Referring to the drawing, which is for illustrative purposes only:

FIG. 1 is a central longitudinal sectional view of a motor embodying the invention with certain portions thereof shown in elevation;

FIG. 2 is a sectional view on line 22 of FIG. 1, the lower half being shown in elevation; and

FIG. 3 is a sectional view on line 3-3 of FIG. 1.

More particularly describing the invention, the motor includes a cylindrical shell having three radial apertures designated 12, 14 and 16, respectively. The apertures 12 and 14 are interchangeably inlet or outlet ports. Aperture 16 is a relief port for carrying off fluid accumulating in a chamber 18. Any suitable fittings may be applied at the apertures for attachment of conduits to carry the motive fluid.

One end of the shell is closed by a relatively thickwalled end plate or plug 20 which is retained by a snap ring 22. The plug 20 is formed with a peripheral groove 28 within which is seated a sealing ring 30 of suitable elastomeric material. The outer end portion of member 20 is beveled at 31 to accommodate the snap ring 22 and permit the end face 32 to be aligned with the end edge of the shell 10. The plug is formed with an in- Wardly projecting annulus or skirt 34 having a conoidal inner surface 35.

Centrally located within the plug is a cylindrical socket or recess 36, a portion of which is defined by an annular lip or boss 37 which projects inwardly of the main body of plug 20. A plurality of angularly disposed passages 42 are provided extending from the inner face of the plug into the socket 36. A hearing 44 is seated in the recess 36, being provided with a central passage or bore 46 and with lateral passages 48 communicating with a peripheral groove 49 and through this with passages 42 in plug 20. The inner face 52 of bearing 44 is spherically concave to act as a bearing seat for a wobble plate 54 having an annular, convex spherical bearing surface 55 which seats against face 52. One or more shims 56 are provided between the base of the socket 36 and the end of the hearing as required. The wobble plate is carried on a crank pin 58 of a crank shaft 60 which will be more fully described later.

Within the shell there is disposed an inner assembly comprising an outer body 62 and an inner body 63, these being of unequal length but both terminating at their outer ends in abutment with an end plate 64 which is secured to member 62 by a plurality of screws 65. Part 63 is assembled in part 62 by a shrink fit and the inner assembly mounted in shell 10 by a shrink fit. Subsequently the entire assembly consisting of shell 10, bodies 62 and 63, end plate 64 and screws 65 are furnace-brazed to form an integral unit. If desired the heads of the screws can be ground off after the brazing operation.

The outer body 62 is formed to provide a circumferential series of cylinders or piston chambers designated 67, shown as twelve in number, preferably being in number a multiple of four. The inner end of member 62 terminates short of the end plug 20 serving to define in part with the plug the aforementioned chamber 18. The cylinder or piston chambers 67 extend the length of member 62 and open into chamber 18, each being provided with a piston 70 of a length such that it projects beyond the inner end of the housing for engagement with the wobble plate 54.

The outer body 62 is formed to provide a pair of axially spaced peripheral grooves or channels of T-shape in cross section, designated 72 and 74, respectively which intersect the cylinders or piston chambers 67. The ports 12 and 14, one of which may serve as inlet and the other as outlet, communicate directly with the channels 72 and 74 respectively. Additionally the body 62 is formed to provide a pair of inwardly extending radial ports and 82 from each cylinder. The latter port, in each case, may be formed by drilling a hole 84 completely through the outer body. It will be noted that the grooves or channels 72, 74 are staggered relative to the ports 80 and 82, the port 82 being located between the channels 72 and 74. Port 80 is located at the end of the cylinder.

The inner body 63, which extends inwardly of the end plate 64 only a short distance beyond the ports 82, is formed with a plurality of helically disposed peripheral grooves or channels which are encased by the inner surface 91 of the outer body 62 thereby forming an individual passage from the port 82 of each cylinder to the port 80 of another cylinder. Each groove or channel 90 extends 90 circumferentially around the periphery of the member 63 establishing communication between the port 82 of one cylinder and the port 80 of another cylinder which is disposed circumferentially 90 therefrom. As will later appear, the pistons 70 act as valves to control fluid flow in these passages.

The crank shaft 60 is centrally mounted within the inner body 63 being supported by a needle bearing 96 in a counterbore 97 of the body and by a pair of ball bearings 98 in a counterbore 99. The outermost bearing 98 extends through an opening 100 in the end plate 64. A ring 101 seated against a shoulder 102 on the shaft, is used to take up end play in the shaft 60, suitable shims 103 being used to locate the parts. A cup-type seal ring 105 of suitable resilient material is provided against the shoulder 106 in the counterbore 97. The crankshaft 60 is stepped to provide the bearing surfaces 108 and 109 for the bearings 96 and 98 respectively.

At its inner end the crankshaft has a wedge-shaped enlargement 112 from which extends the angularly disposed crankpin 58, the latter terminating just short of the face 52 of bearing 44. The shaft crankpin 58 rotates in the wobble plate which has a hub portion 114 and a flange or disk portion 116 against which the pistons 70 impinge or bear.

The pistons 70 each include two cylindrical end sections designated 120 and 121 respectively, and an intermediate section 122 of reduced cross section. Section 121 is slightly longer than section 120 and terminates in a conical end face 124 for engagement with the face 125 of the wobble plate. The sections 120 and 121 closely slidably fit the cylinders and each piston is driven against the wobble plate by pressure fluid admitted to the cylinder through port 80 behind the section 120 of the piston. The pistons are each substantially the same length as the outer body 62 in FIG. 1. The piston in the upper half of the figure is shown extended at the end of its power stroke while the piston at the bottom of the figure is shown retracted.

As previously indicated, the pistons serve as valves to control the flow of pressure fluid to and from the cylinders for operating the pistons and for this purpose the two sections 120 and 121 of each piston are of appropriate length to properly cooperate with channels 72, 74 and port 82 of its particular cylinder alternately to connect port 82 with the channels 72 and 74. In this connection it may be pointed out that the pistons should move in equal distances in both directions beyond the points of valve cutoff at the inner limits or edges of the channels 72 and 74 and this can be effected by adjustment of the shaft and wobble plate through use of appropriate shims 56.

In the operation of the motor, while pressure fluid may be applied to either the opening 12 or 14 and fluid exhausted from the other, by way of example, assuming 12 to be the inlet which is supplied with pressure fluid from any suitable source, this fluid (preferably hydraulictype oil, although a gas can be used), entering port 12 fills the annular channel 72 and is admitted successively to the outer ends of the cylinders as the pistons 70 serve to establish communication between cheannel 72 and ports 82. Thus, during a portion of each stroke of a piston, pressure fluid is free to flow from channel 72 through the cylinder 67 along the stem 122 of the piston to and through port 82 and thence through the associated spiral passage 90 to the port 80 at the outer end of a cylinder which is spaced 90 from the controlling cylinder. Likewise, during a portion of each stroke of a piston, communication is established between the port 82 and the exhaust channel 78 and exhaust port 14. In the manner described the pistons are successively operated or driven on their power strokes against the wobble plate, causing the latter to oscillate or wob ble in a manner well known in the art thereby to rotate the crankshaft 60.

Although I have shown and described a preferred form of my invention, I contemplate that various changes and modifications can be made therein within departing from the scope of the invention as set forth in the claims.

"I claim:

1. In a wobble-plate-type fluid motor, a cylindrical housing shell, a cylindrical outer body fitting within said shell, a cylindrical inner body fitted within said outer body, a crankshaft journaled in said inner body and having a crankp'in disposed beyond the inner ends of said inner and outer bodies, a wobble plate on said crankpin,

said outer body being formed to provide a plurality of axially extending cylindrical piston chambers open at the end of the body adjacent said wobble plate, a piston in each chamber and projecting therefrom into engagement with said wobble plate, said shell and said outer body providing a fluid inlet passage and a fluid outlet passage to each chamber and terminating in axially spaced inlet and outlet ports, respectively, intermediate the ends of the chamber, said inner body being formed to provide a series of fluid passages connecting the outer end of each chamber with another chamber at a point intermediate the inlet and outlet ports thereof, each of said pistons being constructed and arranged to act as a valve for connecting the inlet port of its associated chamber to the fluid passage leading therefrom to another chamber during a portion of its stroke and for connecting the outlet port of its associated chamber to the fluid passage leading therefrom to the same other chamber during a different portion of its stroke.

2. A fluid motor as set forth in claim 1 in which the fluid passages in the inner body comprise helical grooves in the periphery of the inner body enclosed by said outer body.

3. A fluid motor as set forth in claim 1 in which the fluid passages in the inner body comprise helical grooves in the periphery of the inner body enclosed by said outer body and in which the number of cylinders is a multiple of four, and in which one cylinder controls the fluid passage leading to a cylinder spaced circumferentially therefrom.

4. In a valving and fluid distribution means, an annular first member providing a plurality of axially extending cylindrical chambers and providing an inlet port and an outlet port to each cylinder, said ports being spaced axially of the chamber, a piston valve member in each chamber adapted to control said ports, a second annular member, said members being fitted one within the other, said second member having grooves in the surface thereof adjacent the first member and said first member serving to cover said grooves, said first member providing a first port between each chamber and one of said grooves and a second port between each chamber and another of said grooves, said first port being positioned to be controlled by the piston valve member in the chamber.

5. A valving and fluid distribution means as set forth in claim 4 in which said second member closely fits within said first member and in which the adjacent surfaces of said members are cylindrical.

6. A valving and fluid distribution means as set forth in claim 4 in which said grooves are helically disposed.

7. In a fluid motor, a cylindrical outer body, a cylindrical inner body fitted within said outer body, said outer body being formed to provide a plurality of axially extending cylindrical piston chambers therein, said outer body providing a fluid inlet port to each chamber, and, axially spaced therefrom, a fluid outlet port for each chamber, said inner body having a plurality of grooves in its periphery, said outer member covering said grooves, said outer member providing a first port between a first portion of each chamber and one groove and providing a second port between a second portion of each chamber and another groove, and a piston in each chamber adapted to serve as a valve to control said inlet and outlet ports and successively connect the same to said first port.

8. In a fluid motor, a cylindrical housing shell, a cylindrical outer body fitted within said shell, a cylindrical inner body fitted within said outer body, a crankshaft journaled in said inner body and having a crankpin extending beyond the inner ends of said inner and outer bodies, a wobble plate on said crankpin, said outer body being formed to provide a plurality of axially extending cylindrical piston chambers open at the end of the body adjacent said wobble plate, a piston in each chamber and projecting therefrom into engagement with said wobble plate, said outer body having a pair of axially spaced peripheral channels intersecting said piston chambers, said shell having an inlet port communicating with one of said channels and having an outlet port communicating with the other of said channels, said inner body being formed to provide a series of fluid passages connecting the outer end of each chamber with another chamber at a point intermediate the regions of intersection of peripheral channels with the chamber, each of said pistons being constructed and arranged to act as a valve for connecting one of said peripheral channels to the fluid passage leading from the chamber to another cylinder during a portion of its stroke and for connecting the other of said pe- References Cited in the file of this patent UNITED STATES PATENTS 1508;623 Somervell Sept. 16, 1924 2,127,773 Horton Aug. 23, 1938 2,678,536 Morgan May 18, 1954 2,892,310 Mercier June 30, 1959 

